The First Episode Of Brain Structure Abnormalities In Patients With Mild To Moderate Depression And The Effect Of Cognitive Behavioral Therapy On Its Brain Structure

Major depressive disorder(MDD)has attracted global attention due to its high prevalence and severe consequences.Currently,cognitive behavioral therapy(CBT)has been widely used in the treatment of MDD and has become the first-line treatment of MDD.However,due to the influence of other uncontrollable factors such as the insufficient treatment compliance of subjects,there are few studies on the mechanism of CBT in the treatment of MDD using imaging methods at home and abroad.To explore the pathogenesis of MDD and the mechanism of early and stable CBT treatment,this study recruited first-episode patients with mild-to-moderate MDD(n=33)and matched healthy controls(HC)(n=29)in Nanjing Brain Hospital.Two groups of subjects completed clinical assessments and magnetic resonance imaging(MRI)scan within 48 hours of enrollment.After that,the patients with MDD received CBT once a week for the first 12 weeks.After 12 weeks,they received maintenance treatment every four weeks.Clinical assessments and MRI scan were performed again at week 6 and week 28.The voxel-based morphometry(VBM),fractional anisotropy(FA)and mean diffusivity(MD)calculations were applied to study the structural changes of grey matter(GM)and white matter(WM)respectively.The results were as follows:(1)The results of t test indicated that the MDD baseline group had enlarged GM volume in the left medial frontal gyrus(mFG)(t=3,97)than the HC baseline group,and deficits in the left frontal gyrus(MFG)(t=-3.85);increased fractional anisotropy(FA)value of the superior temporal gyrus(STG)(t=3�99)and superior frontal gyrus(SFG)(t=3.51),and decreased FA value of the left precentral gyrus(t=-3.25);decreased mean diffusivity(MD)value of the postcentral gyrus(r=-4.18).MDD 6-weeks group had increased FA value of the right STG(t=3.54)and left SFG(t=3.57)than the HC baseline group;increased MD value of the inferior temporal gyrus(ITG)(t=3.69)and left SFG(t=3.66),and decreased MD value of the left MFG(t=-3.79).MDD 28-weeks group had enlarged GM volume in the right precuneus(t=2.92)than the HC baseline group,and deficits in the left inferior frontal gyrus(IFG)(t=-2.79)and insula(t=-3.25).GM volume in the left mFG(r=-.364,p<0.05)and FA value of the right STG(r=-.439,p<0.05)were negatively correlated with HAMD-24 scale score,while MD value of left MFG(r=.477,p<0.05)was positively correlated with it.(2)The results of ANOVA indicated that the GM volume of the MDD baseline group,MDD 6-weeks group and MDD 28-weeks group were significantly different in the right parahippocampal gyrus(F=4.32),right ITG(F=8.10),left middle temporal gyrus(MTG)(F=6.72),right lenticular nucleus right(F=3.84),inferior parietal lobule(IPL)(F=4.55),right precentral gyrus(F=4.46)and right postcentral gyrus(F=4.57);MD value was significantly different in right IFG(F=11.56),right lingual gyrus(F=7.04),left mFG(F=8.65),right precentral gyrus(F=13.49)and left precentral gyrus(F=7.61);FA value showed no significant difference.This study drew the following conclusions:(1)Compared with HC group,GM abnormalities in MDD group were mainly concentrated in the frontal lobe,including MFG and mFG;WM abnormalities were mainly concentrated in the temporal lobe,including STG and ITG.CBT can play a certain role in the recovery of brain structure abnormalities in patients,and the increase of GM volume in the precuneus may indicate that CBT takes effect through this change.(2)CBT can affect the brain structure of MDD patients,and its effect on GM involved multiple regions such as the temporal lobe,parietal lobe and limbic system,while the effect on WM was mainly concentrated in the frontal lobe.Early CBT had less effect on brain structure,while stable CBT had more effect on brain structure.Moreover,the MD value first decreased and then increased,which was believed to be related to the treatment characteristics of CBT.